RODENTIA. 



393 



the testes are contained. The testes are 

 moreover, remarkable for tneir great size, 



Fig. 281. 



Male generative organs of the If are. 



a, glans penis ; b, body of penis ; c, prostate gland ; 

 d, vesiculae seminales ; e, the urinary bladder ; f, g, 

 testicles ; h, i, epididymis ; k, I, the two scrotal 

 pouches ; p, q, vasa deferentia. 



which generally exceeds that of the kidneys ; 

 a circumstance which is more remarkably 

 evident during the season of copulation. 



From the testicles situated as above, the 

 vasa deferentia ascend into the abdominal 

 cavity,along with the spermatic vessels, through 

 the external abdominal ring. In some tribes, 

 a little above their insertion, the walls of the 

 vasa deferentia become manifestly thicker, and 

 the cavity of their duct considerably dilated ; 

 in some cases they join together, and seem to 

 form but one canal ; but this appearance is 

 merely external, the ducts continuing separate 

 throughout their whole length. 



The vesicul-te seminales, or their analogues, 

 exist in all the Rodentia. In the hares they 

 are simple bags (fig. 281. d); but, generally 

 speaking, their cavity is more or less convo- 

 luted, or branched out into caeca, as, for ex- 

 ample, in the agouti (fig. 282. i, i), and in the 

 beaver (fig. 284. o, p). In most of the genera 

 of this order of quadrupeds the vesiculae 

 seminales are remarkable for their great de- 

 velopment ; in the Guinea-pig they form two 

 long conical tubes, which taper much towards 

 their extremities, but are slightly sacculated 

 for a portion of their length ; the excretory 

 ducts in this animal open into the urethra by 

 an orifice common to them, and to the vasa 

 deferentia. 



In the agouti each opens separately into 

 the common cavity of the verumontanum, in 

 which are also situated the separate orifices 

 of the vasa deferentia, and of the excretory 

 canals of the accessory vesicles ; so that all 



these canals are brought into communication 

 by means of this chamber. 



In the Alpine marmot, the vesicula? semi- 

 nales contain internally a very complicated 

 cavity, the walls of which are glandular. 



In the rats, properly so called, the vesieula3 

 seminales consist of large membranous blad- 

 ders of a flattened conical form, with their 

 inner margins sacculated and uneven, some- 

 thing like a cock's comb. In these animals 

 they are in great part situated out of the pel- 

 vis on account of their very la ge size ; in the 

 hamsters, the voles (Arvicolce),ihe dormice, and 

 the jerboas they present a similar structure, 

 and become remarkably developed during the 

 season for copulation. 



Fig. 282. 



The generative organs of the male Agouti. 



a, a stylet introduced into the cul-de-sac, at the 

 extremity of the penis; b,b, serrated bony plate, 

 situated on each side of the glans penis ; c, c, vasa 

 deferentia ; d, the body of the penis ; e, e, the pro- 

 states ;/, canal of urethra laid open ; g, h, a style in- 

 troduced through the prostatic duct into the ure- 

 thra ; i, i, the vesiculse seminales ; /, m, a wire 

 passed along their duct k, into the urethra ; o, o, 

 Cowper's glands, communicating with the urethra 

 by means of the duct, p, into which a style q has 

 been passed ; , the anus ; r, anal gland with the 

 style, s, t, passed into its duct. 



In the hare and in the rabbit these organs 

 are represented by the single sac already 

 alluded to (fig. 281. d\ the size of which is 

 considerable ; this sac is of a triangular shape, 

 two of its three corners being sometimes con- 

 siderably elongated ; its walls are membranous, 

 except for about two thirds of its upper side, 

 where they are formed by a thick glandular 

 substance something resembling in texture 

 the prostate gland. This sac opens into the 

 urethra by a single orifice excavated in the 

 centre of the verumontanum, which receives 



